Root/gTLD RTTs from Three Sites
Nevil Brownlee, CAIDA | The University of Auckland
IEPG, San Francisco, March 2003
- Overview
- Earlier DNS RTT Work
- NeTraMet meters at UCSD and other sites
- DNS root/gTLD Performance web page
- Data from each meter, updated once each day
- Problem: when interesting events happened, we only saw them from one site
- Now we have three sites, UC San Diego, CU Boulder, U Auckland
- Data collected since mid-Jan 03, we're starting to analyse it
- Do we see correlations between the sites?
- Well, in general, no
- We often see odd things happen on one or two sites
- We don't often see things happen on all sites at the same time
- G root looks overloaded from all sites on weekdays
- But in nine weeks of data, we've seen
- One blip for B root
- One blip each for B, C, D and G gTLD
- Two weeks of small daily spikes for H gTLD
- Typical RTT plots: H gTLD for week starting 15 Mar 03
- Several sections of missing data (meter /data collection failures)
- Some behaviour common to all gTLDs at cu (local link congestion)
- Little steps on one or two sites+gTLDs, e.g. D step on ua and ucsd
- Correlation: H gTLD, five weekdays, 17-20 Feb 03
- Arrows show events, once each day, observed at all three sites
- traceroute for the sites:
cu - cwnet - sprintlink - Amsterdam - h gtld ucsd - calren - qwest - sprintlink - Amsterdam - h gtld ua - clear - alternet - sprintlink - Amsterdam - h gtld - Last 10 hops are common (the trans-Atlantic/European hops),
correlated spikes occured at gTLD or in the common hops - Other uncorrelated changes, e.g. steps for Boulder, Auckland,
happened closer to the observing site - Congestion at Boulder is local to their access link,
it appeared for
all the roots and gTLDs
- Correlations: D gTLD Thu 13 Feb 03
- traceroute for the sites:
cu - att - qwest - d gtld ucsd - calren - qwest - d gtld ua - clear - alternet - qwest - d gtld - Last 5 hops are common (from svlcore-01 in qwest),
correlated steps occured at gTLD or in the common hops
- traceroute for the sites:
- Correlations: C gTLD Wed 12 Feb 03
- traceroute for the sites:
cu - att - atdn - c gtld ucsd - calren - qwest - level3 - atdn - c gtld ua - clear - alternet - level3 - atdn - c gtld - ucsd and ua share much of the path (from Los Angeles via level3)
- But cu takes a completely different path -
only its last hop is the same as for ucsd and ua - Correlated steps occured at gTLD or in the common last hop
- traceroute for the sites:
- Conclusion
- Over nine weeks of data, we see few correlated events.
The root and gTLD servers (and the paths to them) are working well - We do see some correlated events, these can occur for
paths
with many or few hops in common
- caution, the traceroutes were made on 13 Mar 03, long after the events - We have a long-term project to do better analysis,
its goal is to provide daily reports of `interesting' behaviour - Until we have more sites, with different paths to the roots/gTLDs,
we can't say the events happen at the servers - We need NeTraMet meters at more observing sites. Please see
https://www.caida.org/~nevil > Setting up a NeTraMet meter
for more information
- Over nine weeks of data, we see few correlated events.
Last updated: 13 March 2003